1. Technical Field
The present invention relates to a buckle device for holding a webbing belt in a state in which the webbing belt restrains the body of a vehicle occupant, in a seat belt device of a vehicle.
2. Background Technology
The proximal end of a webbing belt, which forms a seat belt device for restraining the body of a vehicle occupant seated in a seat of avehicle, is anchored on the take-up shaft of a retractor provided, for example, at the side of the seat. In contrast, the distal end of the webbing belt is fixed to an anchor plate provided in a vicinity of the retractor.
Further, an intermediate portion of the webbing belt in the longitudinal direction thereof passes through an insert-through hole formed in a through-anchor above the retractor, e.g., at an upper end side of the center pillar of the vehicle, and is folded back downwardly.
The webbing belt between the portion folded over at the through-anchor and the other end passes through an insert-through hole of a tongue plate. Accordingly, due to the tongue plate being pulled, the webbing belt, which is taken-up on the take-up shaft of the retractor, is pulled out. In the state in which the webbing belt is pulled-out in this way, by connecting the tongue plate to a buckle device, which is provided at the side of the seat opposite the side at which the retractor is provided, the webbing belt is set in an applied state.
On the other hand, when an infant or a child who has not yet reached a given age rides in a vehicle, a so-called child seat must be attached to the vehicle, and the infant or child must ride in the child seat.
As a structure for attaching this type of child seat to the vehicle, there is a structure in which the child seat is placed on the seat, and which fixes the child seat by the webbing belt being engaged with and connected to the child seat and the tongue plate being connected to the buckle device as described above.
However, in vehicles of recent years, in addition to the above-described seat belt device, a so-called air bag device is mounted which, at the time when the vehicle rapidly decelerates, expands and unfolds a bag body at the front side of the vehicle occupant such that the vehicle occupant, who attempts to move toward the front of the vehicle due to the inertia at the time of the rapid deceleration of the vehicle, is caught by the bag body. In a vehicle in which this type of air bag device is mounted, when a child seat is attached onto the seat, it is preferable to make the air bag device, which corresponds to that seat, not operate.
As a mechanism for making the air bag device not operate when a child seat is attached, there is a method in which a load sensor is mounted to a vehicle seat, and which, on the basis of the load applied to the seat, judges whether a general vehicle occupant is seated on the seat or a child seat is attached, and which controls the air bag device on the basis of the results of judgement.
However, there is a great dispersion of body weights of vehicle occupants who sit on the seat. Thus, in a method which judges whether or not a child seat is attached on the basis of the load applied to the seat, it is difficult to set a threshold value which becomes the criterion for this judgement.
Further, a method has been thought of in which a device for detecting a child seat is provided separately at the vehicle, and which reliably detects and judges whether or not a child seat is mounted. However, it is difficult to newly provide a special device within the extremely limited space within the vehicle interior, and the costs of requiring a new vehicle design and the like increase. Thus, it is desirable to add a mechanism which can reliably detect whether a child seat is or is not attached, to an existing device or member such as the above-described buckle device or the like.
In view of the aforementioned, an object of the present invention is to provide a buckle device which enables various detections which are based on the pulling-out of the webbing belt, such as the attachment of a child seat or the like.
In order to achieve the above-described object, the present invention recited in claim 1 is a buckle device holding a tongue plate mounted to an elongated, strip-shaped webbing belt which is taken-up and accommodated from a proximal end side toward an accommodating direction side which is opposite to a pull-out direction, by an accommodating urging force which increases and decreases in accordance with an amount by which the webbing belt is pulledout toward a pull-out direction side, said buckle device comprising: a device main body into which the tongue plate is inserted from a distal end side; a latch which is provided at the device main body so as to be movable so as to approach and move away from the tongue plate inserted in the device main body, and which, by moving to approach the tongue plate, mechanically engages with the tongue plate, and limits movement of the tongue plate in a separating direction which is opposite to an insertion direction into the device main body; an anchor member which is mounted to a predetermined position of a vehicle, and which supports the device main body such that the device main body is relatively movable in a predetermined range in the insertion direction and the separating direction; urging means for urging the device main body in the insertion direction with respect to the anchor member, by urging force which is greater than the accommodating urging force in a state in which the webbing belt is pulled out by a predetermined length; a force sensor which is mounted to one of the anchor member and the device main body, and which outputs a load detection signal which is based on pushing force applied from one of the insertion direction and the separating direction; and a pushing member applying pushing force to the force sensor in accordance with relative movement of the device main body in the separating direction with respect to the anchor member.
The present invention recited in claim 2 has the feature that, in the buckle device recited in claim 1, the force sensor has a strain gauge whose electrical resistance value varies in accordance with application of external force and cancellation of applied external force, and, on the basis of a change in the electrical resistance value, the force sensor detects one of that the pushing force is applied and that application of the pushing force is cancelled.
The present invention recited in claim 3 has the feature that, in the buckle device recited in claim 2, the force sensor has: a case accommodating a diaphragm to which the strain gauge is mounted; and a transfer rod whose proximal end contacts the diaphragm, and whose other end side projects from a hole formed in a side wall of the case, and which receives the pushing force at an exterior of the case, and the transfer rod, which has received the pushing force, one of pushes the strain gauge directly and pushes the strain gauge indirectly via the diaphragm.
The present invention recited in claim 4 has the feature that, in the buckle device recited in claim 3, the force sensor has a gel-like sealing means which is provided at an interior of the case and which seals the strain gauge at an interior.
The present invention recited in claim 5 has the feature that, in the buckle device recited in claim 4, a plate spring is the urging means and the pushing member, and the plate spring is structured so as to include: a mounting piece fixed to one of the anchor member and the device main body to which the force sensor is not mounted; and a plate portion formed integrally with the mounting piece and pressed into contact with the force sensor, and due to relative movement of the device main body in the separating direction with respect to the anchor member, pushing force which the plate portion applies to the force sensor increases.
The present invention recited in claim 6 has the feature that the buckle device recited in claim 5 further comprises a rivet which passes through a long hole, whose longitudinal direction is along the insertion direction and the separating direction and which is formed in one of the anchor member and the device main body, and a through-hole, which is formed in another of the anchor member and the device main body, and the device main body is connected by the rivet so as to be movable with respect to the anchor member along the insertion direction and the separating direction, and one of the plate spring and the force sensor is fixed on the rivet, and one of the plate spring and the force sensor which is not fixed on the rivet is fixed to the one of the anchor member and the device main body in which the long hole is formed.
The present invention recited in claim 7 has the feature that, in the buckle device recited in claim 1, a plate spring is the urging means and the pushing member, and the plate spring is structured so as to include: a mounting piece fixed to one of the anchor member and the device main body to which the force sensor is not mounted; and a plate portion formed integrally with the mounting piece and pressed into contact with the force sensor, and due to relative movement of the device main body in the separating direction with respect to the anchor member, pushing force which the plate portion applies to the force sensor increases.
The present invention recited in claim 8 has the feature that the buckle device recited in claim 7 further comprises a rivet which passes through a long hole, whose longitudinal direction is along the insertion direction and the separating direction and which is formed in one of the anchor member and the device main body, and a through-hole, which is formed in another of the anchor member and the device main body, and the device main body is connected by the rivet so as to be movable with respect to the anchor member along the insertion direction and the separating direction, and one of the plate spring and the force sensor is fixed on the rivet, and one of the plate spring and the force sensor which is not fixed on the rivet is fixed to the one of the anchor member and the device main body in which the long hole is formed.
The present invention recited in claim 9 has the feature that, in the buckle device recited in claim 2, a plate spring is the urging means and the pushing member, and the plate spring is structured so as to include: a mounting piece fixed to one of the anchor member and the device main body to which the force sensor is not mounted; and a plate portion formed integrally with the mounting piece and pressed into contact with the force sensor, and due to relative movement of the device main body in the separating direction with respect to the anchor member, pushing force which the plate portion applies to the force sensor increases.
The present invention recited in claim 10 has the feature that the buckle device recited in claim 9 further comprises a rivet which passes through a long hole, whose longitudinal direction is along the insertion direction and the separating direction and which is formed in one of the anchor member and the device main body, and a through-hole, which is formed in another of the anchor member and the device main body, and the device main body is connected by the rivet so as to be movable with respect to the anchor member along the insertion direction and the separating direction, and one of the plate spring and the force sensor is fixed on the rivet, and one of the plate spring and the force sensor which is not fixed on the rivet is fixed to the one of the anchor member and the device main body in which the long hole is formed.
The present invention recited in claim 11 has the feature that, in the buckle device recited in claim 3, a plate spring is the urging means and the pushing member, and the plate spring is structured so as to include: a mounting piece fixed to one of the anchor member and the device main body to which the force sensor is not mounted; and a plate portion formed integrally with the mounting piece and pressed into contact with the force sensor, and due to relative movement of the device main body in the separating direction with respect to the anchor member, pushing force which the plate portion applies to the force sensor increases.
The present invention recited in claim 12 has the feature that the buckle device recited in claim 11 further comprises a rivet which passes through a long hole, whose longitudinal direction is along the insertion direction and the separating direction and which is formed in one of the anchor member and the device main body, and a through-hole, which is formed in another of the anchor member and the device main body, and the device main body is connected by the rivet so as to be movable with respect to the anchor member along the insertion direction and the separating direction, and one of the plate spring and the force sensor is fixed on the rivet, and one of the plate spring and the force sensor which is not fixed on the rivet is fixed to the one of the anchor member and the device main body in which the long hole is formed.
In the buckle device recited in claim 1, the tongue plate which is attached to the elongated, strip-shaped webbing belt is inserted into the device main body from the distal end side of the tongue plate. In this state, due to the latch approaching the tongue plate and mechanically engaging with the tongue plate, the tongue plate and the device main body are mechanically connected. In this way, movement of the tongue plate in the separating direction at the time when the tongue plate is removed from the device main body is restricted.
Accordingly, in this state in which movement is restricted by the latch, if the webbing belt is made to span across the front side of the body of a vehicle occupant seated on the seat, a webbing belt applied state arises, and the body of the vehicle occupant is restrained by the webbing belt.
On the other hand, the above-described webbing belt is urged toward the accommodating direction side (i.e., toward the proximal end side of the webbing belt) by a predetermined accommodating urging force. Accordingly, in the state in which tension (tensile force) based on the accommodating urging force is applied to the webbing belt and the tongue plate is inserted in the device main body, this tension attempts to remove the tongue plate from the device main body.
Here, the device main body is connected so as to be movable over a predetermined range in the insertion direction and the separating direction of the tongue plate, with respect to the anchor member which connects the device main body to the vehicle. Thus, when the aforementioned tension is applied to the latch which engages with the tongue plate via the tongue plate which is inserted in the device main body, the device main body attempts to move in the separating direction with respect to the anchor member via the latch.
However, because the device main body is urged in the insertion direction by the urging means, provided that tension exceeding the urging force of the urging means, i.e., accommodating urging force at the time the webbing belt is pulled out by a predetermined length or more, is not applied, the device main body cannot be moved in the separating direction with respect to the anchor member.
On the other hand, when tension (i.e., accommodating urging force) against the urging force of the urging means is applied to the webbing belt, and the device main body thereby moves toward the separating direction side with respect to the anchor member, the pushing member pushes the force sensor in accordance with this movement. A load detection signal of a predetermined level is outputted from the force sensor which has received the pushing force in this way.
As described above, in order for the device main body to move toward the separating direction with respect to the anchor member, the accommodating urging force which resists the urging force of the urging means must be applied to the webbing belt. In order for the accommodating urging force which resists the urging force of the urging means to be applied to the webbing belt, the webbing belt must be pulled out by a predetermined length or more.
Thus, as described above, due to the force sensor being pushed by the pushing member, it can be detected that the webbing belt has been pulled out by a predetermined length or more.
Accordingly, for example, by making the urging force of the urging means be greater than the accommodating urging force corresponding to the pulled-out amount of the webbing belt needed to restrain the body of a vehicle occupant seated on the seat, and making the urging force of the urging means be smaller than the accommodating urging force corresponding to the pulled-out amount of the webbing belt needed to fix a child seat on the seat, it can be detected whether or not a child seat is attached on the seat.
Note that, as described above, detection of a child seat is given as one example of an applied example of the present invention. However, it is to be additionally remarked that the present invention is not limited to the detection of a child seat.
In the buckle device recited in claim 2, when the urging force of the urging means exceeds the accommodating urging force and the device main body moves in the separating direction with respect to the anchor member, the pushing force from the pushing member is applied either directly or indirectly to the strain gauge of the force sensor. The strain gauge to which the pushing force is applied deforms slightly, and the electrical resistance value changes due to this deformation. Accordingly, by detecting the change in the electrical resistance value of the strain gauge, it can be detected whether or not the device main body has moved relative to the anchor member, i.e., whether or not the webbing belt has been pulled out by a predetermined length or more.
Here, the electrical resistance value of the strain gauge generally varies linearly with respect to changes in the pushing force applied to the strain gauge. Thus, the pulled-out amount of the webbing belt can be detected if it is a predetermined length or more. In this way, for example, it can be applied not only to detection of a child seat, but also to various types of controls and the like such as control of a so-called pretensioner mechanism or a force limiter or the like, and further, it can be used in a plurality of different controls.
Note that the strain gauge in the present invention is a generic term for elements which utilize the piezoresistance effect which is the fact that, when strain is applied to a resistor which is metal or a semiconductor, the resistance value changes, and which convert a physical amount such as pressure or load or the like into an electric signal. Examples thereof are metal strain gauges, semiconductor strain gauges, and the like. As semiconductor strain gauges, there are a diffusion type, a bulk type, a deposition type, and the like. However, the strain gauge in the present invention is not limited to any of these various types of strain gauges, and it does not matter if the strain gauge is appropriately selected on the basis of the structure of the entirety of or the respective regions of the buckle device.
In the buckle device recited in claim 3, the distal end side of the transfer rod passes through and projects out from a hole formed in the side wall of the case. When the urging force of the urging means exceeds the accommodating urging force and the device main body moves in the separating direction with respect to the anchor member, pushing force is applied to the distal end of the transfer rod, and the pushing force attempts to push the transfer rod into the interior of the case.
The proximal end of the transfer rod contacts the diaphragm accommodated in the case. When pushing force is received as described above, the diaphragm is pushed by the transfer rod. In this way, the diaphragm deforms slightly. Because the strain gauge is mounted to the diaphragm, when the diaphragm deforms as described above, the strain gauge also deforms. In this way, the electrical resistance value of the strain gauge varies.
In the buckle device recited in claim 4, the strain gauge is sealed in the gel-like sealing means. Thus, foreign matter such as dust and the like does not adhere to the strain gauge, and the effects of changes in humidity and the like are small. In this way, over a long period of time, the pushing force can be correctly detected, and accordingly, it can correctly be detected whether or not the webbing belt has been pulled out by a predetermined length or more.
In accordance with the buckle device recited in claim 5, the mounting piece of the plate spring serving as the urging means is fixed to the one of the anchor member and the device main body to which the force sensor is not mounted. Further, the plate spring has a plate portion, and this plate portion contacts the force sensor. When the urging force of the urging means exceeds the accommodating urging force and the device main body moves in the separating direction with respect to the anchor member, the plate spring elastically deforms. In this way, the pushing force, by which the plate portion pushes the force sensor, increases, and this increased pushing force is detected by the force sensor.
In the buckle device of claim 6, the long hole is formed in one of the anchor member and the device main body, and the through-hole is formed in the other, and the rivet passes through the long hole and the through-hole. Because the longitudinal direction of the long hole is along the aforementioned insertion direction and separating direction, the rivet can move from a state of contacting one end portion in the longitudinal direction of the long hole to a state of contacting the other end portion. In this way, in the present buckle device, the device main body can be connected so as to be displaceable over a predetermined range with respect to the anchor member along the insertion direction and the separating direction.
Further, in the present buckle device, the plate spring or the device main body is fixed on the rivet. In contrast, the one of the plate spring and the device main body which is not fixed on the rivet is fixed to the one of the anchor member and the device main body in which the long hole is formed.
When the rivet moves within the long hole when the urging force of the urging means exceeds the accommodating urging force and the device main body moves in the separating direction with respect to the anchor member, among the plate spring and the force sensor, the one which is fixed on the rivet approaches the one which is not fixed on the rivet. In this way, the pushing force, which the plate portion of the plate spring receives from the force sensor, increases, and accompanying this, the pushing force which the plate portion applies to the force sensor increases.
In accordance with the buckle device recited in claim 7, the mounting piece of the plate spring serving as the urging means is fixed to the one of the anchor member and the device main body to which the force sensor is not mounted. Further, the plate spring has a plate portion, and this plate portion contacts the force sensor. When the urging force of the urging means exceeds the accommodating urging force and the device main body moves in the separating direction with respect to the anchor member, the plate spring elastically deforms. In this way, the pushing force, by which the plate portion pushes the force sensor, increases, and this increased pushing force is detected by the force sensor.
In the buckle device of claim 8, the long hole is formed in one of the anchor member and the device main body, and the through-hole is formed in the other, and the rivet passes through the long hole and the through-hole. Because the longitudinal direction of the long hole is along the aforementioned insertion direction and separating direction, the rivet can move from a state of contacting one end portion in the longitudinal direction of the long hole to a state of contacting the other end portion. In this way, in the present buckle device, the device main body can be connected so as to be displaceable over a predetermined range with respect to the anchor member along the insertion direction and the separating direction.
Further, in the present buckle device, the plate spring or the device main body is fixed on the rivet. In contrast, the one of the plate spring and the device main body which is not fixed on the rivet is fixed to the one of the anchor member and the device main body in which the long hole is formed.
When the rivet moves within the long hole when the urging force of the urging means exceeds the accommodating urging force and the device main body moves in the separating direction with respect to the anchor member, among the plate spring and the force sensor, the one which is fixed on the rivet approaches the one which is not fixed on the rivet. In this way, the pushing force, which the plate portion of the plate spring receives from the force sensor, increases, and accompanying this, the pushing force which the plate portion applies to the force sensor increases.
In accordance with the buckle device recited in claim 9, the mounting piece of the plate spring serving as the urging means is fixed to the one of the anchor member and the device main body to which the force sensor is not mounted. Further, the plate spring has a plate portion, and this plate portion contacts the force sensor. When the urging force of the urging means exceeds the accommodating urging force and the device main body moves in the separating direction with respect to the anchor member, the plate spring elastically deforms. In this way, the pushing force, by which the plate portion pushes the force sensor, increases, and this increased pushing force is detected by the force sensor.
In the buckle device of claim 10, the long hole is formed in one of the anchor member and the device main body, and the through-hole is formed in the other, and the rivet passes through the long hole and the through-hole. Because the longitudinal direction of the long hole is along the aforementioned insertion direction and separating direction, the rivet can move from a state of contacting one end portion in the longitudinal direction of the long hole to a state of contacting the other end portion. In this way, in the present buckle device, the device main body can be connected so as to be displaceable over a predetermined range with respect to the anchor member along the insertion direction and the separating direction.
Further, in the present buckle device, the plate spring or the device main body is fixed on the rivet. In contrast, the one of the plate spring and the device main body which is not fixed on the rivet is fixed to the one of the anchor member and the device main body in which the long hole is formed.
When the rivet moves within the long hole when the urging force of the urging means exceeds the accommodating urging force and the device main body moves in the separating direction with respect to the anchor member, among the plate spring and the force sensor, the one which is fixed on the rivet approaches the one which is not fixed on the rivet. In this way, the pushing force, which the plate portion of the plate spring receives from the force sensor, increases, and accompanying this, the pushing force which the plate portion applies to the force sensor increases.
In accordance with the buckle device recited in claim 11, the mounting piece of the plate spring serving as the urging means is fixed to the one of the anchor member and the device main body to which the force sensor is not mounted. Further, the plate spring has a plate portion, and this plate portion contacts the force sensor. When the urging force of the urging means exceeds the accommodating urging force and the device main body moves in the separating direction with respect to the anchor member, the plate spring elastically deforms. In this way, the pushing force, by which the plate portion pushes the force sensor, increases, and this increased pushing force is detected by the force sensor.
In the buckle device of claim 12, the long hole is formed in one of the anchor member and the device main body, and the through-hole is formed in the other, and the rivet passes through the long hole and the through-hole. Because the longitudinal direction of the long hole is along the aforementioned insertion direction and separating direction, the rivet can move from a state of contacting one end portion in the longitudinal direction of the long hole to a state of contacting the other end portion. In this way, in the present buckle device, the device main body can be connected so as to be displaceable over a predetermined range with respect to the anchor member along the insertion direction and the separating direction.
Further, in the present buckle device, the plate spring or the device main body is fixed on the rivet. In contrast, the one of the plate spring and the device main body which is not fixed on the rivet is fixed to the one of the anchor member and the device main body in which the long hole is formed.
When the rivet moves within the long hole when the urging force of the urging means exceeds the accommodating urging force and the device main body moves in the separating direction with respect to the anchor member, among the plate spring and the force sensor, the one which is fixed on the rivet approaches the one which is not fixed on the rivet. In this way, the pushing force, which the plate portion of the plate spring receives from the force sensor, increases, and accompanying this, the pushing force which the plate portion applies to the force sensor increases.